Drill bit



9 1964 J. w. GRAHAM ETAL 3,163,242

DRILL BIT Original Filed May 13, 1959 2 Sheets-Sheet 1 INVENTORS.

JOHN w. e AHAM, LEON H. R NSON,JR.,

Dec. 29, 1964 1 w, GRAHAM ETAL 3,163,242

DRILL BIT Original Filed May 13, 1959 2 Sheets-Sheet 2 INVENTORS.

JOHN w. GRAH LEON H. ROBIN ,JR., BY

United States Patent 3,163,242 DRILL BIT John W. Graham and Leon H. Robinson, In, Houston,

Tex., assignors, by mesne assignments, to Jersey Production Research Company, Tulsa, 01:121., 2 corpora- .tion of Delaware Original application May 13, 1959, Ser. No. 312,864, now Patent No. 3,678,934, dated Feb. 26, 1963. Divided and this application May 25, 1962, Ser. No. 197,674

6 Claims. (Cl. 175331) The present invention is directed to a drill bit. More particularly, the invention is concerned with drilling a well in which increased drilling rates are obtained. In its more specific aspects, the invention is concerned with an improved drill bit and method for drilling a well.

This application is a division of Serial No. 812,864, filed May 13, 1959, now US. Patent 3,078,934, for John W. Graham and Leon H. Robinson, Jr., entitled Drilling of Earth Formations by Extrusion.

The present invention may be briefly described as a drill bit for drilling a well in which a body member attached to a drill string has a drill member mounted on the body member for contacting earth formations. The drill member is formed to provide a plurality ofopenended passageways with at least one of the ends of each of the passageways being formed to contact the earth formation peripherally in drilling of the well. Each of the passageways discharge into the well or into the circulating drilling fluid which in turn. is discharged into the well, whereby a portion of the earth formation is extruded through each of the passageways in contact with the earth formation. r

The drillmember may be rotatably or rigidly mounted on the body member and the drill member may. be substantially a sphere or the drill member'may be -a toothed roller with the passageways being formed in the teeth or in a band in the outer edge of the tooth roller. .The drill member may be cone-shaped and the band may be on thebase of the cone with the passageways discharging below the band adjacent the teeth.

In drilling of wells, it is believed that the stress distribution within the rock is in part responsible for the slow drilling which is frequently encountered. The rock may be tectonically relaxed in a particular area of interest and thus the principal stresses within the rock may be equal. However, if a hole is drilled through this area, the hole will create discontinuities and stresses, particularly at or near the bottom of the hole. For example, the outer edge of the borehole may be under considerable compression because of the discontinuity caused by the presence of the hole. Moreover, the greater the sharpness of the corners (that is, the smaller the radius of the curvature), the greater will be the compressional stresses around the periphery of the hole. Stresses that are superimposed over the stress of the rock are those created by hydrostatic pressure of the fluid in the borehole, the overburden pressure caused by the weight of the formation, and the fluid pressure in the pores of the formation.

In areas where the subsurface rock fails malleably while drilling, an ideal situation would make full use of the compressional stresses existing at the bottom of the borehole. The drill bits employed in the art, however, do not take advantage of the stresses created by the borehole. It is therefore a feature of the present invention not only to exploit the stresses in existence but also to generate additional stresses within the rock which will increase drilling rates. This is done by imposing pressure on the earth formation pierced by the well at a plurality of spacedapart points and extruding a portion of the formation from the bottom of the well through the drill bit at a tacting the bottom 13 of the well with the tooth 14, which plurality of points the periphery of each of said plurality of points where the pressure is imposed.

This may be accomplished in a number of Ways and, therefore, the invention will be further described by reference to the drawings in which: a

FIG. 1 is a sectional view of 'a bit tooth of a preferred embodiment of the present invention in contact with the tion;

FIG. 4a is a partial sectional view of FIG. 4; FIG. 5 is a still further modification of the present invention; and

FIG. 5a is a bottom view of the device of FIG. 5. Referring now to the drawing and 'particularlyto FIG. 1,

numeral 11 designates the wall of a well drilled from the earths surface, not shown, and having a drill bit 12 carried on the lower end of a drill string, not shown, conis provided with a tapered passageway drilled through the tooth and opening into the well. These holes 15 may be from A; to A inch in diameter and may be arranged in the outer ring of teeth on each cone of a hard rock bit. When the tooth 14 contacts the formation and begins to destroy the formation immediately below the bit 12, a portion of the formation is extruded into and ultimately passes through the passageway 15 and discharges into the annulus 16 and then is removed from the well with the drilling fluid. As the tooth continues its jourhey, the extruded rock removed from the region B in the bottom of the well 13 leaves a small hole below the zone of the destruction normally produced by the bit. This small hole produces stresses in the rock because of the discontinuity of the bottom of the hole just as the'discon tinuity produced by the borehole 11 induces compressional stresses around the periphery of the borehole. Accordingly, destruction of the rock is increased immediately surrounding the region B from whichthe rock is extruded, and therefore increased drilling rates are obtained.

In ordinary drilling operations, the solid bit teeth of conventional bits cause regions A surrounding each tooth to fail by brittleness and thus small rock chips are created therein. No advantage is taken of the tremendous malle ability existing immediately below each bit tooth. The improved bit and method of drilling with the passage way 15 in the bit tooth 14 allows the rock to deform malleably through the tooth and hence is removed permanently from region B. i p

In FIG. 2, a modified bit 20 having a body 21 has a plurality of roller cutters 22 rotatably mounted on the body 21. In the improved bit 20 of the present invention, the cone-shaped roller 22 has a band 23 on the outer edge of each of the cones provided with a plurality of openended passageways 24 tapering to a larger opening 25 immediately above the teeth 26 which are adjacent the apex of the cone. The holes 24 are suitably placed in the center of the band and are tapered with the smaller opening on the side of the band which contacts the bottom of the well, as shown in FIG. 2a. It is considered that, in the practice of the present invention, the teeth 26 may also be provided with passageways which allow rock to be extruded therethrough.

Referring now to FIG. 3 which shows a modification of FIG. 2, the band 23' is provided with a plurality of teeth 27 shaped like an elephants foot and formed with FIG. 4illustrates a bit embodying the present inven- I a plurality of open-ended passageways 28. These teeth have a large bearing surface and may be provided with a plurality of the tapered holes 28, as shown in FIG. 3a, .As'

shown in the drawing, the bearing surface is fiat. As a modification of FIG. 3, all of the teeth of the. device of FIG. 3 may be of the elephant foot type.

As afurther modification of the present'invention, a

body member 30 in FIG. 4,*which suitably may be a drill collarattached to a drill string, is provided with a plurality .ofmud ports 31 for circulation of drill fluid and has a spindle 32 rigidly attached thereto on which is rotatably mountthe sphere 33 and spindle 32. In drilling with the device of FIG. 4 and FIG. 4a, the sphere 33 by virtueof its'eccentric arrangement on the spindle 32 revolves off-center around the spindle 32 and the rock is extruded into and passes through the passageways .34 and carried vup' the hole with'the drilling fluid. Also, rotation of the sphere I 33 causes abrasion of the bottom and wall of the hole,

thus advancing the bit through the formation being drilled. As a still further modification of the present invention,

i and passes ;through 'saidplurality of said p sageways as shown inFIGS. 5 and 5a, a body membersu'ch as40 Y 7 provided with mud ports 41 has formed thereon a plurality of spikes 42, each ofwhich has an open-ended passageway 43 terminating at thebottomflof the spikepand discharging within the cavity 44 which, in turn, discharges V v U V v v member, a toothed roller member rotatably mounted on into the well through mud ports 41. The spikes 42' may be constructed of tungsten carbide and may also have diamonds mounted onthe periphery of the spikes 42 such that when the improved device 40 is rotated and reciprocated, a scratching or churning action accompaniesthe extrusion action of the rock through the passageways "143. The spikes 42, on contacting thebottom of the well, form channels with concentric shells of formation material between'the channels. 'The shells are crushed as the bit penetrates the formation and the crushed material, as well 6 as the extruded material, is carried upwardly with the drilling fiuid. V v The present invention is quite advantageous'and useful in thatby imposingpressure on the rock, it becomes malleable and' is'causedto' be extruded, creating additional stresses within the rock being drilled and tliius contributing to improved drilling operations.

The invention will be further described by reference to the following operation in which water-saturated carthage marble was subjected to a confining pressure of 10,000 psi. A tubular member having a inch opening next to its face compressed the confinedmarble about 0.25 inch". The marble yielded and'd'eformed malleably which caused member, at least one drilling member'carried on the free end of said body member for contacting an earth formation, said drilling member extending outwardly from said body member and being formed to provide a plurality of obstruction-free, open-ended passageways which extend through at least a portion of said drilling member, the drilling member being formed for contacting said earth formationsimultaneouslyunder sufiicient confinihg pressure at a plurality of points peripherally of the lower end of a plurality of said passageways in drilling of said well, with the upper endof each of said passageways discharging into said well free of contact with said earth formation whereby a portion of said earthformatibrris extruded into and passes through said plurality of passageways simultaneously in contact with said earth formation.

;2. .A drill bit for drilling a well which comprises a body 7 member, a substantiallyLsPherical drill member eccentri cally mounted orr said libdy menib'r for 'conta ting an ar'thformation, said drill member being. formed to vide a 'plura'lity of open-ended passageways, said drill member being adapted to jcontactsaid earth formation simul taiieously'under suifici'entcorifi ning pressure at aplu'rality of points peripherally of thlower nfi Of a plurality of said passageways in drilling of said well an thiup'per end of'each of said passagewaysdi barging I the well ed into whereby a portion of said earth f simultaneously in contact with. saidearthformation.

" 3. A drill bit in accordance with claim 2m whieli the said body member, said roller member having a plurality of. open-ended passageways'formed in at least selected of said teeth, said roller member being adapted to contact said earth formation simultaneously under sufficient can; fining pressure at a plurality of points peripherally of the lower end of a plurality of said" passageways in drilling of said well and the upperend of each of said passage: ways discharging into said well whereby a portion of said earthform'ation is extruded into and passes through said plurality of said passageways simultaneously inscontact t a ea thfor at qm a 5. A drill bit in accbrdancewith claim l in which' the drilling member comprises a plurality of drill teeth having passageways extending therethroug li.

6. A drillbit inaccdrdarice with am 1 injwhich' the drilling member comprises a plurality of drill teeth,- each having a flat bearing surface, said drill teeth having said llat'bearing surface being formed'to provide" a plurality of said passageways.

Refr'ent's Cited the file of this patent UNITEl STATES PATENTS 

1. A DRILL BIT FOR DRILLING A WELL WHICH COMPRISES A BODY MEMBER, AT LEAST ONE DRILLING MEMBER CARRIED ON THE FREE END OF SAID BODY MEMBER FOR CONTACTING AN EARTH FORMATION, SAID DRILLING MEMBER EXTENDING OUTWARDLY FROM SAID BODY MEMBER AND BEING FORMED TO PROVIDE A PLURALITY OF OBSTRUCTION-FREE, OPEN-ENDED PASSAGEWAYS WHICH EXTEND THROUGH AT LEAST A PORTION OF SAID DRILLING MEMBER, THE DRILLING MEMBER BEING FORMED FOR CONTACTING SAID EARTH FORMATION SIMULTANEOUSLY UNDER SUFFICIENT CONFINING PRESSURE AT A PLURALITY OF POINTS PERIPHERALLY OF THE LOWER END OF A PLURALITY OF SAID PASSAGEWAYS IN DRILLING OF SAID WELL, WITH THE UPPER END OF EACH OF SAID PASSAGEWAYS DISCHARGING INTO SAID WELL FREE OF CONTACT WITH SAID EARTH FORMATION WHEREBY A PORTION OF SAID EARTH FORMATION IS EXTRUDED INTO AND PASSES THROUGH SAID PLURALITY OF PASSAGEWAYS SIMULTANEOUSLY IN CONTACT WITH SAID EARTH FORMATION. 